XAML with MultiDataTrigger and NullToBoolConverter

我将您的转换器更改为此，因为它似乎要简单得多…

public class NullToBoolConverter : IValueConverter
{
    public object Convert(object value, Type targetType, object parameter, CultureInfo culture)
    {
        if (value == null)
            return false;
        string currentValue = value.ToString();
        if (string.IsNullOrWhiteSpace(currentValue))
            return false;
        return true;
    }
    public object ConvertBack(object value, Type targetType, object parameter, CultureInfo culture)
    {
        return Binding.DoNothing;
    }
}

那么你的XAML样式应该是这样的…

    <ex:NullToBoolConverter
        x:Key="NullToBoolConverter" />
    <Style
        x:Key="okButtonStyle"
        TargetType="{x:Type Button}">
        <Setter
            Property="IsEnabled"
            Value="False" />
        <Style.Triggers>
            <MultiDataTrigger>
                <MultiDataTrigger.Conditions>
                    <Condition
                        Binding="{Binding ElementName=Hostadress, Path=Text, Converter={StaticResource NullToBoolConverter}, UpdateSourceTrigger=PropertyChanged}"
                        Value="True" />
                    <Condition
                        Binding="{Binding ElementName=UserBox, Path=Text, Converter={StaticResource NullToBoolConverter}, UpdateSourceTrigger=PropertyChanged}"
                        Value="True" />
                    <Condition
                        Binding="{Binding ElementName=PasswordTextBox, Path=Text, Converter={StaticResource NullToBoolConverter}, UpdateSourceTrigger=PropertyChanged}"
                        Value="True" />
                    <Condition
                        Binding="{Binding ElementName=PortBox, Path=Text, Converter={StaticResource NullToBoolConverter}, UpdateSourceTrigger=PropertyChanged}"
                        Value="True" />
                </MultiDataTrigger.Conditions>
                <Setter
                    Property="IsEnabled"
                    Value="True" />
            </MultiDataTrigger>
        </Style.Triggers>
    </Style>

调试工作，输入所有文本框将启用按钮。

请注意，我将Binding语句更改为使用ElementName和Path。

我简化了一点代码:

[ValueConversion(typeof(object), typeof(bool))]
public class NullToBoolValueConverter : IValueConverter
{
    public object Convert(object value, Type targetType, object parameter, CultureInfo culture)
    {
        var result = value == null;
        return parameter != null ? !result : result;
    }
    public object ConvertBack(object value, Type targetType, object parameter, CultureInfo culture)
    {
        return value;
    }
}

我试过你的代码，我你唯一的问题是你只比较null的值，而不是string.Empty。试试这个

public object Convert(object value, Type targetType, object parameter, CultureInfo culture)
{
    TypeConverter converter = TypeDescriptor.GetConverter(typeof(bool));
    bool nullResult = false;
    if (parameter != null)
        nullResult = (bool)converter.ConvertFrom(parameter);
    if (value == null || value.ToString() == string.Empty)
        return nullResult;
    else
        return !nullResult;
}